United States Department of Agriculture

Forest Service FS-1029 October 2014 

USDA Forest 

Service and 

USDA Agricultural 

Research Service 

Joint Strategic 

Framework on the 

Conservation and 

Use of Native Crop 

Wild Relatives in the 

United States

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On February 25, 2011, the USDA Forest Service 

and USDA Agricultural Research Service signed 

a Memorandum of Understanding (10-MU11132421-334) formalizing collaboration between 

the agencies in activities related to the conservation, 

management, and restoration of native plant species 

and their habitats and ecosystems. 

Further, this strategic framework responds to 

Executive Order (E.O.) 13603, National Defense 

Resources Preparedness. Section 201 of E.O. 13603 

addresses the responsibilities of Department 

Secretaries.

Sec. 201. Priorities and Allocations Authorities. 

(a) The authority of the President conferred 

by section 101 of the Act, 50 U.S.C. App. 2071, 

to require acceptance and priority performance 

of contracts or orders (other than contracts of 

employment) to promote the national defense over 

performance of any other contracts or orders, and to 

allocate materials, services, and facilities as deemed 

necessary or appropriate to promote the national 

defense, is delegated to the following agency heads:

(1) the Secretary of Agriculture with respect to 

food resources, food resource facilities, livestock 

resources, veterinary resources, plant health 

resources, and the domestic distribution of farm 

equipment and commercial fertilizer;

Agency Collaboration

Recognizing the value of crop wild relatives 

(CWR) of native plants for crop improvement 

and providing for the current and future food 

security of the United States and the world, 

the Forest Service and Agricultural Research 

Service, agencies of the U.S. Department of 

Agriculture (USDA), have developed this 

strategic framework for collaboration that 

will help ensure the conservation, evaluation, 

and use of native CWR occurring on National 

Forest System lands. 

Purpose

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Native Plants and Crop Wild Relatives

Introduction

Crop Wild Relatives (CWR) are native wild plant 

species that are genetically related to crops, 

including food, forage, medicinal, ornamental, 

industrial, and forest tree crops. They are a diverse 

group of plants that occur in a wide variety of natural 

habitats throughout the world. Some of them are 

widely distributed, while others are restricted to very 

small areas. Some are very common, while others are 

rare and endangered. 

Species of CWR generally have more genetic 

diversity than the related crop species because they 

have not passed through the genetic bottleneck of 

domestication. Many of them have characteristics 

that allow them to survive under a wider range of 

environments and stresses than crop plants. Genes 

from CWR have been used by farmers in crop 

improvement for thousands of years by encouraging 

weedy relatives to grow alongside crop plants, 

allowing natural crossing. 

In the early 20th century, Nikolai Vavilov and other 

early proponents of genetic resources conservation 

recognized the potential value of CWR in plant 

breeding. CWR species have been in use in plant 

breeding programs for many decades, providing 

genes for improvement to banana, barley, bean, 

cassava, chickpea, corn, lettuce, oat, millet, potato, 

rice, sugarcane, sunflower, tomato, and wheat, among 

others. Some of the traits transferred from CWR to 

these crops include: 

•	 improved pest and disease resistance

•	 tolerance to abiotic stresses

•	 increased yield

•	 novel cytoplasm

•	 quality traits

Continuing developments in molecular technologies 

that make the transfer of traits between species easier 

improves the prospects for even greater use of CWR 

in the future.

Khoury, et al. (2013) published a national CWR 

inventory for the United States. Currently, the list 

contains 4,600 species from 985 genera and 194 plant 

families. The inventory includes both wild species 

that can contribute genetic traits to our crops and 

those that can be used directly for food, forage, and 

other uses. In addition to native species, it includes 

nonnative CWR that have become naturalized in the 

United States. 

Since supporting food security is the primary goal for 

conserving and managing CWR, the activities within 

this framework focus on CWR related to food crops. 
 Among the CWR of the United States are the 

wild ancestors of several domesticated food plants 

(including sunflower, strawberry, pecan, blueberry, 

and cranberry) and other species closely related to 

food crops that originated both in North America 

and in other areas of the world. Many of these species 

have proven valuable in modern crop improvement 

efforts to support American and world agriculture. 

Native species in the genus Helianthus (sunflower) 

have provided genes 

for resistance to several 

diseases, such as rust, 

downy mildew, powdery 

mildew, broomrape, 

Sclerotinia (white mold) 

head rot and stalk rot, and 

resistance to insects such 

as sunflower moth. These genes have been successfully 

transferred into cultivated sunflower. Resistance to 

the phylloxera louse (Phylloxera vitifoliae Fitch), which 

first devastated European vineyards in the late 1800s, 

is provided to this day by using North American 

grape species, especially Vitis rupestris, V. riparia, and 

V. cinerea var. helleri, as rootstocks. Juglans hindsii, 

native to northern California, is used as a rootstock for 

orchards of English walnut around the world.

As with all forms of biodiversity, populations of CWR 

and the genetic diversity they contain are threatened 

by factors such as habitat loss and fragmentation, land 

use changes, pollution, climate change, fire, invasive 

species, and exploitation. They have often been 

overlooked when conservation priorities have been set 

at the international, national, or local level. A major 

step in advancing the recognition of conservation 

of CWR as an important issue came in 1961 when a 

Food and Agriculture Organization (FAO) Technical 

Meeting emphasized the need to preserve the entire 

genepools of crops, including their wild relatives. 

The worldwide focus on 

conservation of CWR increased 

in the 1980s and 1990s. The 

inclusion of CWR conservation 

in international treaties (the 

Convention on Biological 

Diversity (CBD) in 1992, the 

FAO International Undertaking 

on Plant Genetic Resources (later replaced by the 

International Treaty on Plant Genetic Resources for 

Food and Agriculture, 2001), and the Global Plan 

of Action for Plant Genetic Resources for Food and 

Agriculture in 1996 and 2011) elevated awareness of 

this issue. The Global Strategy for Plant Conservation 

2011–2020, adopted by the Conference of the Parties 

to the CBD, includes Target 9. Target 9 specifies that 

70 percent of the genetic diversity of crops, including 

their wild relatives and other socioeconomically 

valuable plant species, are conserved, while respecting, 

preserving, and maintaining associated indigenous and 

local knowledge. 

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Nikolai Vavilov

supporting food security is the primary goal 

for conserving and managing CWR” 

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A small, fiery, round wild pepper (Capsicum annuum

var. glabriusculum) is native from Northern South 

America to the Southern United States. Known as 

chiltepin, it is an ancestor of hundreds of sweet and 

hot pepper varieties found in markets and grocery 

stores today (jalapeno, poblano, mirasol, cayenne, bell, 

and others). Habanero and Tabasco are two varieties 

of peppers that did not originate from chiltepin.

Chiltepins are the oldest, as well as the hottest, wild 

pepper in the Americas. They grow on the rocky 

surfaces of steep slopes and are difficult to find 

because they grow in among other shrubs.

The Coronado National Forest in Arizona has 

reserved 2,500 acres in the “Wild Chile Botanical 

Area” that provides in situ habitat for the largest 

population of chiltepin peppers north of Mexico. In 

situ populations of crop wild relatives provide genetic 

material for use in crop improvement.

I

n situ conservation refers to the maintenance of 

reproducing organisms in nature, specifically in 

the areas where they developed their distinctive 

properties. 

Ex situ conservation refers to the maintenance of 

germplasm (seeds, pollen, living plants, and plant 

parts) in human-made sites, such as genebanks 

and botanical gardens. In situ conservation allows 

plant populations to continue to evolve and adapt 

to changing environmental conditions in nature. 

By preserving entire populations rather than 

subsamples, a greater amount of genetic diversity can 

be conserved under in situ conditions than under ex 

situ conditions. In situ conservation is important as 

CWR plant populations continue to adapt to changes 

in environmental conditions, with respect to CWR 

gene ecology. In situ conservation of CWR contributes 

to ecosystem services and supports traditional cultural 

practices. Ex situ conservation is required for purposes 

of research, ease of access, and secure storage of 

germplasm. Ex situ collections safeguard plant genetic 

resources against loss and provide the rapid access to 

germplasm needed by the research and conservation 

community. They are, however, often expensive and 

difficult to maintain, particularly for undomesticated 

plants that are difficult to regenerate and lack speciesspecific conservation protocols. The plants do not 

evolve under natural forces and processes. 

Conservation is most effective when a complementary 

approach involving both in situ and ex situ strategies 

is employed. The two strategies act as backups to each 

other and maximize the potential for cost-effective, 

long-term conservation of alleles, genotypes, and 

populations.

Native Crop Wild Relatives 

Chiltepin Pepper: “The Mother of all Peppers”

Complementary Conservation

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Mountain Meadow Seeds

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Native Crop Wild Relatives

T

he main activities within the framework will fall under two general approaches. The first approach will 

focus on the CWR of a specific crop. The second approach will focus on a specific protected area and 

the CWR conserved within its borders. Each approach will have an in situ component and an ex situ 

component. The two approaches are detailed below.

Maintain documentation of all CWR conserved in situ and ex situ on the publicly accessible database of the 

NPGS (Germplasm Resources Information Network [GRIN], http://www.ars-grin.gov/npgs/index.html). 

Identify a specific crop based on one 

or more of the following factors: 

economic value of the crop, National 

Plant Germplasm System (NPGS) 

curator-identified need, available 

resources to accomplish the project, 

and USDA Forest Service special 

interest.

In situ conservation

Identify that crop’s CWR that are 

native to the United States. 

Identify populations of the CWR 

that occur on USDA Forest Service 

lands. 

Sample selected populations of 

each of the CWR to measure 

genetic diversity. 

Designate specific populations 

for each of the CWR as In Situ 

Genetic Resource Reserves 

(IGRRs) on USDA Forest Service 

lands. For evaluation criteria, 

include ecogeographic zone, 

population size, sustainability, 

current level of protection by 

the USDA Forest Service, ease 

of access for monitoring and 

germplasm collection, distance 

from other IGRRs, and genetic 

profile (uniqueness, allelic 

diversity, etc.).

Develop or modify current USDA 

Forest Service management plans 

to include the IGRRs using existing 

guidelines.

Ex situ conservation

Collect propagules (seeds in most 

cases) and documentation for 

both medium- and long-term 

conservation in the NPGS.

a. From all populations designated 

as IGRRs

b. From sampled populations that 

have high genetic diversity, but that 

were considered inappropriate for 

designation as IGRRs.

Monitor seed viability in mediumterm seed storage and re-collect 

propagules and associated 

documentation as needed to 

replenish germplasm supplies. 

1. Specific crop approach

Documentation

Activities

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Maintain documentation of all CWR conserved in situ and ex situ on the publicly accessible database of the 

NPGS (GRIN, http://www.ars-grin.gov/npgs/index.html). 

Select a protected area managed by 

the USDA Forest Service for which 

a plant inventory exists or can be 

developed.

In situ conservation

Identify the CWR for all crops 

of interest that occur within the 

protected area. 

Designate the protected area as a 

botanical special area in current 

USDA Forest Service management 

plans if deemed appropriate 

based on number of CWR taxa, 

significance of individual taxa 

as resources for food security, 

uniqueness of CWR taxa, ease 

of access for monitoring and 

germplasm collection, and distance 

from other IGRRs.

Ex situ conservation

Collect propagules and associated 

documentation from CWR in 

the protected area when an NPGS 

curator for one of the related

crops has the interest and 

resources to do so.

Monitor seed viability in mediumterm seed storage and re-collect 

propagules and associated 

documentation as needed to 

replenish germplasm supplies. 

2. Protected area approach

Documentation

Khoury, C.; Greene, S.; Wiersema, J.; Maxted, N.; Jarvis, A.; and Struik, P. 2013. An inventory of crop wild 

relatives of the United States. Crop Science. 53 (4): 1496-1508. DOI: 10.2135/cropsci2012.10.0585.

References

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Native Crop Wild Relatives

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Conservation is most effective when a

complementary approach involving both

in situ and ex situ strategies is employed.” 

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The National Clonal Germplasm Repository (NCGR) 

in Corvallis, OR, is one of the components of the National Plant Germplasm System. This genebank conserves collections of several temperate fruit, nut and 

agronomic crops, including hazelnuts, strawberries, 

hops, pears, currants, gooseberries, raspberries, blackberries, blueberries, and cranberries. The collections 

include both cultivars and wild relatives of the cultivars from around the world. Many of the plants in the 

collections are clonally propagated, but collections of 

wild plants are maintained as seed. 

The collections are evaluated for useful traits, tested for 

virus contamination, documented in a public database, 

and freely distributed to scientists around the world 

for use in breeding, research, and education. For more 

information, go to http://www.ars.usda.gov/main/

site_main.htm?modecode=53-58-15-00.

The Corvallis repository conserves samples of many 

of the wild native fruits and nuts found on national 

forests. These collections provide ex situ backup conservation and can be used to reestablish populations 

if the need arises. They also provide facilitated access 

for research to the genetic resources, which furthers 

scientific understanding and contributes to the improvement of the related crop species. 

Native Crop Wild Relatives

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The National Clonal Germplasm Repository in Corvallis, OR

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Native Crop Wild Relatives

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The Hinds’ Black Walnut:

An Endangered Crop Wild Relative

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Juglans hindsii, the Hinds’ black walnut, is a large tree 

(up to 60 feet tall) endemic to a roughly circular area 

in California centered near Fresno and reaching the 

San Francisco Bay area. 

J. hindsii is endangered, with possibly only a few native 

stands remaining. It grows in riparian woodlands, 

either in single species stands or mixed with 

California’s oaks and cottonwoods. 

J. hindsii is commercially important as a rootstock 

for English walnut (Juglans regia) all over the world, 

both on its own 

and as a parent 

to the fast- growing 

Luther Burbank hybrid, “Paradox” 

J. hindsii x J. regia. J. hindsii is cultivated as an 

ornamental tree wherever it will grow. 

The wood of J. hindsii is commonly called claro walnut 

by the lumber industry and woodworkers. It is used 

to make fine furniture, gun stocks, and large, naturaltop tables because of its durability, good working 

properties, and beauty.

California Walnut Board
Thousands of years ago, Native Americans 

began cultivating the wild native common 

sunflower...today, the sunflower is the fourth 

most important oilseed crop in the world.” 

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USDA Agricultural Research Service

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Native Crop Wild Relatives

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Sunflower - A Native American Crop

Thousands of years 

ago, Native Americans 

began cultivating the 

wild native common 

sunflower, Helianthus 

annuus L. Careful 

selection over hundreds 

of years produced the 

domesticated sunflower 

with single large seed 

heads and enlarged oilrich seeds. Today, the 

sunflower is the fourth 

most important oilseed 

crop in the world and is 

grown in every temperate 

region. 

In all, 52 species of wild 

sunflowers are native 

to North America, with 

the geographic ranges 

of most limited to the 

United States. The wild 

sunflower species are 

adapted to a wide range 

of habitats and have 

much greater variability 

for many traits than the 

cultivated sunflower. 

Modern sunflower crop 

breeding programs have 

used wild species as the 

source of a number of 

traits, including resistance 

to downy mildew, 

rust, powdery mildew, 

broomrape, sclerotinia 

head and stalk rot, and 

sunflower moth. The 

estimated economic 

contribution of the wild 

species to the cultivated 

sunflower is between $269 

and $384 million per year. 

Continued use of the 

tremendous genetic 

diversity present in wild 

sunflower populations 

is critical to meeting 

the future challenges 

of emerging pests and 

environmental changes 

that may threaten 

sunflower production. 

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USDA Agricultural Research Service
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Grapes are one of the oldest cultivated plants—initially 

cultivated in the Mediterranean area and, then, across 

Europe and Asia. Scientists have found grapevine 

fossils that are more than 60 million years old. Humans 

have used grapes for food and wine since the earliest 

times.

The grapes used in winemaking came from only one 

species Vitis vinifera, native to the Mediterranean 

and Asia. Most of the other 50 or so grape species in 

the world are from North 

America. Early French 

colonists in Florida tried 

many times to introduce 

and establish Vitis vinifera 

vineyards. Each time, 

there was a complete crop 

failure, and these failures 

were repeated many times in colonial America. These 

early French viticulturists never discovered the cause 

of the crop failure.

In the late 17th century and early to mid 18th century, 

American botanists and naturalists were sending many 

different species of North American grapes to Europe, 

especially France. Viticulturists were developing 

numerous horticultural cultivars. In the mid to 

late 1850s and the early 1860s, thousands of North 

American grapevines were being shipped to Europe. A 

North American aphid, the grape phylloxera, made its 

way to Europe by 1863. The grape phylloxera attacked 

Vitis vinifera in a manner never observed on North 

American grape species. On most North American 

grape species, this aphid feeds on grape leaves forming 

galls. In Europe, the grape phylloxera attacked Vitis 

vinifera by feeding on its small roots. The aphid injects 

saliva into the roots and then sucks up the sap. The 

aphid’s saliva is toxic to Vitis vinifera. The mystery 

of why the grapes were dying, however, was not 

discovered until 1868 when Professor Planchon and 

his colleagues dug up healthy, dying, and dead Vitis 

vinifera vines. On the “healthy” vines, they discovered 

grape phylloxera attached to the roots. They discovered 

that, by the time the vines were observed dying, the 

aphids had already moved on 

to their next meal. By this time, 

nearly 40 percent of French 

vineyards had been destroyed. 

Eventually, the grape phylloxera 

was defeated by grafting 

Vitis vinifera scions on to the 

phylloxera resistant rootstock of 

the American species Vitis riparia.

By the late 1870s and 1880s, grafting Vitis vinifera 

scions onto an American rootstock, Vitis riparia, 

was generally accepted as the “cure” to keeping Vitis 

vinifera vines alive, healthy, and productive. Thus 

began the tremendously large and expensive program 

of reconstituting all the grapevines in France and other 

European countries by grafting Vitis vinifera cultivars 

on to Vitis riparia rootstock.

Today, populations of Vitis riparia are managed in situ 

(in place) throughout its range in the United States to 

maintain its genetic diversity. If Vitis riparia is needed 

again, scientists will have the crop wild relative to draw 

upon.

Grapes: The Oldest Cultivated Plants

Native Crop Wild Relatives

discovered in 1868...nearly 40 percent of 

French vineyards had been destroyed” 

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USDA Agricultural Research Service

USDA Agricultural Research Service
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Humans have used grapes for food 

and wine since the earliest times.” 

 

‘ ‘
Both the USDA Agricultural Research Service and the 

USDA Forest Service have responsibilities and interests in 

the conservation and management of native plant species 

and their habitats and ecosystems.

The USDA Forest Service is a land management 

agency with the responsibility for 193 million acres of 

National Forest System lands in 43 States and provides 

support in the management of the Nation’s privately 

owned forests. As mandated by Federal law and 

regulations of the Secretary of Agriculture, the agency 

has major responsibility for conserving biodiversity 

through the management of fish, wildlife, and plant 

habitats in forest and grasslands, including providing 

special protection for threatened, en dangered, and 

sensitive/rare plant and animal species. The USDA Forest 

Service accomplishes much of this work by initiating 

and developing cooperative relationships and effective 

external partnerships through its National Forest System, 

Research and Development, and State and Private 

Forestry branches. The USDA Forest Service implements 

germplasm conservation almost exclusively by managing 

and conserving in situ populations. Because the national 

forests and grasslands are managed for native species, 

they can be considered “working” germplasm collections.

The USDA Agricultural Research Service manages the 

National Plant Germplasm System (NPGS), which has 

the responsibility to collect, maintain, distribute, evaluate, 

and preserve genetic resources of plant species of interest 

to the United States. This system is designed to provide, 

on a continuing basis, the plant genetic diversity needed 

by public and private plant scientists to improve the 

productivity of crops and minimize the vulnerability of 

those crops to biological and environmental stresses. The 

NPGS currently maintains more than 556,000 accessions 

representing more than 14,700 species, 2,418 genera, 

and 228 families. Most agronomic and horticultural 

crops that are economically important in the United 

States are actively maintained in the NPGS. Traditional 

NPGS programs have almost exclusively used ex situ 

conservation methods, in which the plant germplasm is 

preserved in genebanks outside of its native habitat. 

About the Partner Agencies

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discrimination in all its programs and activities on the 

basis of race, color, national origin, age, disability, and 

where applicable, sex, marital status, familial status, 

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part of an individual’s income is derived from any public 

assistance program. (Not all prohibited bases apply to 

all programs.) Persons with disabilities who require 

alternative means for communication of program 

information (Braille, large print, audiotape, etc.) should 

contact USDA’s TARGET Center at (202) 720-2600 

(voice and TDD). To file a complaint of discrimination, 

write USDA, Director, Office of Civil Rights, 1400 

Independence Avenue, S.W., Washington, D.C. 20250-

9410, or call (800) 795-3272 (voice) or (202) 720-6382 

(TDD). USDA is an equal opportunity provider and 

employer.

The use of trade or firm names in this publication is for 

reader information and does not imply endorsement by 

the U.S. Department of Agriculture of any product or 

service. 

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